Aza boron-pyridyl-isoindoline analogues
- Zhang, Hui, Wu, Yanping, Fan, Minhui, Xiao, Xuqiong, Mack, John, Kubheka, Gugu, Nyokong, Tebello, Lu, Hua
- Authors: Zhang, Hui , Wu, Yanping , Fan, Minhui , Xiao, Xuqiong , Mack, John , Kubheka, Gugu , Nyokong, Tebello , Lu, Hua
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232912 , vital:50037 , xlink:href="https://doi.org/10.1039/C7NJ00707H"
- Description: Several aza boron-pyridyl-isoindoline analogues are synthesized through a facile and scale-up two step reaction using 1,2-naphthalenedicarbonitrile as a starting material. These analogues show broad envelopes of intense vibrational bands in the absorption spectra with moderate fluorescence quantum yields in solution and the solid-state. An analysis of the structure–property relationships is described based on X-ray crystallography, optical spectroscopy, and theoretical calculations.
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- Authors: Zhang, Hui , Wu, Yanping , Fan, Minhui , Xiao, Xuqiong , Mack, John , Kubheka, Gugu , Nyokong, Tebello , Lu, Hua
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232912 , vital:50037 , xlink:href="https://doi.org/10.1039/C7NJ00707H"
- Description: Several aza boron-pyridyl-isoindoline analogues are synthesized through a facile and scale-up two step reaction using 1,2-naphthalenedicarbonitrile as a starting material. These analogues show broad envelopes of intense vibrational bands in the absorption spectra with moderate fluorescence quantum yields in solution and the solid-state. An analysis of the structure–property relationships is described based on X-ray crystallography, optical spectroscopy, and theoretical calculations.
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Enantioselective electrochemical carbon-chloride bond cleavage of hexachlorocyclohexanes (HCHs) catalyzed by Mn (III) Cl-phthalocyanine
- Wen, Junxia, Yu, Baoqui, Huang, Tingting, Mack, John, Wildervanck, Martijn, Nyokong, Tebello, Li, Minzhi, Zhu, Weihua, Liang, Xu
- Authors: Wen, Junxia , Yu, Baoqui , Huang, Tingting , Mack, John , Wildervanck, Martijn , Nyokong, Tebello , Li, Minzhi , Zhu, Weihua , Liang, Xu
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189252 , vital:44831 , xlink:href="https://doi.org/10.1016/j.jelechem.2017.09.020"
- Description: A lipophilic and electron-rich metallophthalocyanine Mn(III)Cl(α,α′-n-OC5H11)8Pc has been synthesized and characterized. A series of electrochemical experiments demonstrate that the Mn(III)Cl(α,α′-n-OC5H11)8Pc complex can be used as a catalyst for highly efficient carbon-chloride bond cleavage of environmental toxic hexachlorocyclohexanes (HCHs) through electrochemical catalysis, and that the increased catalytic efficiency is related to the enantiomeric carbon-chloride σ-bond of HCHs.
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- Authors: Wen, Junxia , Yu, Baoqui , Huang, Tingting , Mack, John , Wildervanck, Martijn , Nyokong, Tebello , Li, Minzhi , Zhu, Weihua , Liang, Xu
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189252 , vital:44831 , xlink:href="https://doi.org/10.1016/j.jelechem.2017.09.020"
- Description: A lipophilic and electron-rich metallophthalocyanine Mn(III)Cl(α,α′-n-OC5H11)8Pc has been synthesized and characterized. A series of electrochemical experiments demonstrate that the Mn(III)Cl(α,α′-n-OC5H11)8Pc complex can be used as a catalyst for highly efficient carbon-chloride bond cleavage of environmental toxic hexachlorocyclohexanes (HCHs) through electrochemical catalysis, and that the increased catalytic efficiency is related to the enantiomeric carbon-chloride σ-bond of HCHs.
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Characterization of conjugates of NaYF4
- Watkins, Zane, Uddin, Imran, Britton, Jonathan, Nyokong, Tebello
- Authors: Watkins, Zane , Uddin, Imran , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238132 , vital:50589 , xlink:href="https://doi.org/10.1016/j.molstruc.2016.10.011"
- Description: NaYF4:Er/Yb/Gd upconversion nanoparticles (UCNP) capped with amino groups were covalently attached to chloro aluminium tetrasulphonated phthalocyanine (ClAlTSPc) and chloro aluminium tetracarboxy phthalocyanine (ClAlTCPc). The conjugates were characterized using different techniques such as infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). There was a decrease in the intensity of fluorescence emission spectra of the UCNPs at 658 nm in the presence of the phthalocyanines. This decrease indicates an energy transfer between the donor UCNP and conjugated accepting phthalocyanine (Pc), due to Förster resonance energy transfer (FRET). FRET efficiencies of 18% and 21% for ClAlTSPc and ClAlTCPc, respectively, were obtained. Oxygen generation by ClAlTSPc following FRET was proved.
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- Authors: Watkins, Zane , Uddin, Imran , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238132 , vital:50589 , xlink:href="https://doi.org/10.1016/j.molstruc.2016.10.011"
- Description: NaYF4:Er/Yb/Gd upconversion nanoparticles (UCNP) capped with amino groups were covalently attached to chloro aluminium tetrasulphonated phthalocyanine (ClAlTSPc) and chloro aluminium tetracarboxy phthalocyanine (ClAlTCPc). The conjugates were characterized using different techniques such as infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). There was a decrease in the intensity of fluorescence emission spectra of the UCNPs at 658 nm in the presence of the phthalocyanines. This decrease indicates an energy transfer between the donor UCNP and conjugated accepting phthalocyanine (Pc), due to Förster resonance energy transfer (FRET). FRET efficiencies of 18% and 21% for ClAlTSPc and ClAlTCPc, respectively, were obtained. Oxygen generation by ClAlTSPc following FRET was proved.
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Electrocatalytic application for gold nanoparticles decorated sulfur-nitrogen co-doped graphene oxide nanosheets and nanosized cobalt tetra aminophenoxy phthalocyanine conjugates
- Shumba, Munyaradzi S, Nyokong, Tebello
- Authors: Shumba, Munyaradzi S , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188260 , vital:44739 , xlink:href="https://doi.org/10.1016/j.electacta.2017.03.154"
- Description: Sulfur and nitrogen affinity for gold is utilized to self-assemble gold nanorods (AuNRs) on S, N doped or S/N co-doped graphene oxide nanosheets (SGONS/AuNRs, NGONS/AuNRs or SNGONS/AuNRs) for enhancement of the electrocatalytic activity of nanosized cobalt tetra aminophenoxy phthalocyanine (complex 1) towards hydrogen peroxide detection. Of the electrodes containing AuNRs, 1-SNGONS/AuNRs-GCE gave the lowest limits of detection (LOD) of 0.012 μM followed by 1-SGONS/AuNRs-GCE and 1-AuNRs-SNGONS(seq)-GCE both with LOD of 0.016 μM. This work shows that in the absence of GONS (when AuNRs are alone and in the presence of 1 in 1/AuNRs-GCE), unfavorable detection limits are obtained and that doping of GONS is important in improving LOD. 1-SNGONS/AuNRs-GCE showed concentration dependent mechanisms resulting in two adsorption Gibbs energies (ΔGo) of −18.55 kJ mol−1 and −17.35 kJ mol−1 at high and low concentrations, respectively.
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- Authors: Shumba, Munyaradzi S , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188260 , vital:44739 , xlink:href="https://doi.org/10.1016/j.electacta.2017.03.154"
- Description: Sulfur and nitrogen affinity for gold is utilized to self-assemble gold nanorods (AuNRs) on S, N doped or S/N co-doped graphene oxide nanosheets (SGONS/AuNRs, NGONS/AuNRs or SNGONS/AuNRs) for enhancement of the electrocatalytic activity of nanosized cobalt tetra aminophenoxy phthalocyanine (complex 1) towards hydrogen peroxide detection. Of the electrodes containing AuNRs, 1-SNGONS/AuNRs-GCE gave the lowest limits of detection (LOD) of 0.012 μM followed by 1-SGONS/AuNRs-GCE and 1-AuNRs-SNGONS(seq)-GCE both with LOD of 0.016 μM. This work shows that in the absence of GONS (when AuNRs are alone and in the presence of 1 in 1/AuNRs-GCE), unfavorable detection limits are obtained and that doping of GONS is important in improving LOD. 1-SNGONS/AuNRs-GCE showed concentration dependent mechanisms resulting in two adsorption Gibbs energies (ΔGo) of −18.55 kJ mol−1 and −17.35 kJ mol−1 at high and low concentrations, respectively.
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Effects of covalent versus non-covalent interactions on the electrocatalytic behavior of tetracarboxyphenoxyphthalocyanine in the presence of multi-walled carbon nanotubes
- Shumba, Munyaradzi S, Nyokong, Tebello
- Authors: Shumba, Munyaradzi S , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188271 , vital:44740 , xlink:href="https://doi.org/10.1080/00958972.2017.1303679"
- Description: Tetracarboxyphenoxy phthalocyanine was covalently linked to multi-walled carbon nanotubes and the conjugate was used for modification of glassy carbon electrodes for the detection of hydrogen peroxide. The electrocatalytic behavior was examined by cyclic voltammetry, square wave voltammetry, and rotating disk electrode. The results show that covalent linking is attractive in terms of high detecting currents, low overpotential, and high catalytic rate constants. Very low detection limits were observed with CoTCPhPc-DAMN-MWCNT(linked)-GCE at 0.33 nM. The resulting catalytic rate constant was 1.1 × 103 M−1s−1.
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- Authors: Shumba, Munyaradzi S , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188271 , vital:44740 , xlink:href="https://doi.org/10.1080/00958972.2017.1303679"
- Description: Tetracarboxyphenoxy phthalocyanine was covalently linked to multi-walled carbon nanotubes and the conjugate was used for modification of glassy carbon electrodes for the detection of hydrogen peroxide. The electrocatalytic behavior was examined by cyclic voltammetry, square wave voltammetry, and rotating disk electrode. The results show that covalent linking is attractive in terms of high detecting currents, low overpotential, and high catalytic rate constants. Very low detection limits were observed with CoTCPhPc-DAMN-MWCNT(linked)-GCE at 0.33 nM. The resulting catalytic rate constant was 1.1 × 103 M−1s−1.
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Nanocomposites of sulphur-nitrogen co-doped graphene oxide nanosheets and cobalt mono carboxyphenoxy phthalocyanines for facile electrocatalysis
- Shumba, Munyaradzi, Centane, Sixolile, Chindeka, Francis, Nyokong, Tebello
- Authors: Shumba, Munyaradzi , Centane, Sixolile , Chindeka, Francis , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239665 , vital:50753 , xlink:href="https://doi.org/10.1016/j.jelechem.2017.03.006"
- Description: Nanocomposites consisting of cobalt mono carboxyphenoxy phthalocyanine (CoMCPhPc) either covalently linked to graphene oxide nanosheets (GONS), sulphur doped graphene oxide nanosheets (SDGONS), nitrogen doped graphene oxide nanosheets (NDGONS) or sulphur/nitrogen co-doped graphene oxide nanosheets (SNDGONS) or sequentially added were used to modify glassy carbon electrode. The modified electrodes were characterised using several techniques: voltammetry, X-ray photon spectroscopy and scanning electron spectroscopy before testing their activity on the detection of hydrogen peroxide at pH 7. The presence of SNDGONS had a significant improvement on the currents as compared to CoMCPhPc modification alone in both sequentially added or covalently linked to MPcs. CoMCPhPc-SNDGONS(seq)-GCE and CoMCPhPc-SDGONS(linked)-GCE resulted in impressive limits of detection and catalytic rate constant values of 1.58 nM and 5.44 nM, 3.07 × 105 M−1 s−1 and 3.01 × 103 M−1 s−1 respectively. Gibbs energy value was determined to be −21.22 kJ mol−1 for CoMCPhPc-SNDGONS(linked)-GCE indicative of a facile spontaneous electroreduction reaction on the surface of this electrode.
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- Authors: Shumba, Munyaradzi , Centane, Sixolile , Chindeka, Francis , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239665 , vital:50753 , xlink:href="https://doi.org/10.1016/j.jelechem.2017.03.006"
- Description: Nanocomposites consisting of cobalt mono carboxyphenoxy phthalocyanine (CoMCPhPc) either covalently linked to graphene oxide nanosheets (GONS), sulphur doped graphene oxide nanosheets (SDGONS), nitrogen doped graphene oxide nanosheets (NDGONS) or sulphur/nitrogen co-doped graphene oxide nanosheets (SNDGONS) or sequentially added were used to modify glassy carbon electrode. The modified electrodes were characterised using several techniques: voltammetry, X-ray photon spectroscopy and scanning electron spectroscopy before testing their activity on the detection of hydrogen peroxide at pH 7. The presence of SNDGONS had a significant improvement on the currents as compared to CoMCPhPc modification alone in both sequentially added or covalently linked to MPcs. CoMCPhPc-SNDGONS(seq)-GCE and CoMCPhPc-SDGONS(linked)-GCE resulted in impressive limits of detection and catalytic rate constant values of 1.58 nM and 5.44 nM, 3.07 × 105 M−1 s−1 and 3.01 × 103 M−1 s−1 respectively. Gibbs energy value was determined to be −21.22 kJ mol−1 for CoMCPhPc-SNDGONS(linked)-GCE indicative of a facile spontaneous electroreduction reaction on the surface of this electrode.
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Characterization of phthalocyanine functionalized quantum dots by dynamic light scattering, laser Doppler, and capillary electrophoresis
- Ramírez-García, Gonzalo, Oluwole, David O, Nxele, Siphesihle Robin, d’Orlyé, Fanny, Nyokong, Tebello, Bedioui, Fethi, Varenne, Anne
- Authors: Ramírez-García, Gonzalo , Oluwole, David O , Nxele, Siphesihle Robin , d’Orlyé, Fanny , Nyokong, Tebello , Bedioui, Fethi , Varenne, Anne
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238184 , vital:50595 , xlink:href="https://doi.org/10.1007/s00216-016-0120-x"
- Description: In this work, we characterized different phtalocyanine-capped core/shell/shell quantum dots (QDs) in terms of stability, ζ-potential, and size at various pH and ionic strengths, by means of capillary electrophoresis (CE), and compared these results to the ones obtained by laser Doppler electrophoresis (LDE) and dynamic light scattering (DLS). The effect of the phthalocyanine metallic center (Zn, Al, or In), the number (one or four), and nature of substituents (carboxyphenoxy- or sulfonated-) of functionalization on the phthalocyanine physicochemical properties were evaluated. Whereas QDs capped with zinc mono-carboxyphenoxy-phtalocyanine (ZnMCPPc-QDs) remained aggregated in the whole analyzed pH range, even at low ionic strength, QDs capped with zinc tetracarboxyphenoxy phtalocyanine (ZnTPPc-QDs) were easily dispersed in buffers at pH equal to or higher than 7.4. QDs capped with aluminum tetrasulfonated phthalocyanine (AlTSPPc-QDs) and indium tetracarboxyphenoxy phthalocyanines (InTCPPc-QDs) were stable in aqueous suspension only at pH higher than 9.0 due to the presence of functional groups bound to the metallic center of the phthalocyanine. The ζ-potential values determined by CE for all the samples decreased when ionic strength increased, being well correlated with the aggregation of the nanoconjugates at elevated salt concentrations. The use of electrokinetic methodologies has provided insights into the colloidal stability of the photosensitizer-functionalized QDs in physiological relevant solutions and thereby, its usefulness for improving their design and applications for photodynamic therapy.
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- Authors: Ramírez-García, Gonzalo , Oluwole, David O , Nxele, Siphesihle Robin , d’Orlyé, Fanny , Nyokong, Tebello , Bedioui, Fethi , Varenne, Anne
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238184 , vital:50595 , xlink:href="https://doi.org/10.1007/s00216-016-0120-x"
- Description: In this work, we characterized different phtalocyanine-capped core/shell/shell quantum dots (QDs) in terms of stability, ζ-potential, and size at various pH and ionic strengths, by means of capillary electrophoresis (CE), and compared these results to the ones obtained by laser Doppler electrophoresis (LDE) and dynamic light scattering (DLS). The effect of the phthalocyanine metallic center (Zn, Al, or In), the number (one or four), and nature of substituents (carboxyphenoxy- or sulfonated-) of functionalization on the phthalocyanine physicochemical properties were evaluated. Whereas QDs capped with zinc mono-carboxyphenoxy-phtalocyanine (ZnMCPPc-QDs) remained aggregated in the whole analyzed pH range, even at low ionic strength, QDs capped with zinc tetracarboxyphenoxy phtalocyanine (ZnTPPc-QDs) were easily dispersed in buffers at pH equal to or higher than 7.4. QDs capped with aluminum tetrasulfonated phthalocyanine (AlTSPPc-QDs) and indium tetracarboxyphenoxy phthalocyanines (InTCPPc-QDs) were stable in aqueous suspension only at pH higher than 9.0 due to the presence of functional groups bound to the metallic center of the phthalocyanine. The ζ-potential values determined by CE for all the samples decreased when ionic strength increased, being well correlated with the aggregation of the nanoconjugates at elevated salt concentrations. The use of electrokinetic methodologies has provided insights into the colloidal stability of the photosensitizer-functionalized QDs in physiological relevant solutions and thereby, its usefulness for improving their design and applications for photodynamic therapy.
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Singly and Doubly N-Confused Calix [4] phyrin Organoplatinum (II) Complexes as Near-IR Triplet Sensitizers
- Pushpanandan, Poornenth, Maurya, Yogesh Kumar, Omagari, Toshihiro, Hirosawa, Ryuji, Ishida, Masatoshi, Mori, Shigeki, Yasutake, Yuhsuke, Fukatsu, Susumu, Mack, John, Nyokong, Tebello, Furuta, Hiroyuki
- Authors: Pushpanandan, Poornenth , Maurya, Yogesh Kumar , Omagari, Toshihiro , Hirosawa, Ryuji , Ishida, Masatoshi , Mori, Shigeki , Yasutake, Yuhsuke , Fukatsu, Susumu , Mack, John , Nyokong, Tebello , Furuta, Hiroyuki
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233144 , vital:50061 , xlink:href="https://doi.org/10.1021/acs.inorgchem.7b02047"
- Description: Organoplatinum(II) complexes of calix[4]phyrin analogues, singly N-confused calix[4]phyrin (Pt-2), and doubly N-confused calix[4]phyrin (Pt-3), were synthesized and characterized. The explicit structures of these organoplatinum(II) complexes were elucidated by single-crystal X-ray diffraction and spectroscopic studies. The introduction of N-confused pyrrole rings to the parent calix[4]phyrin scaffold was found to have profound effects on the photophysical properties, such as the bathochromic shifts of both the absorption and phosphorescence maxima. The triplet excited state properties of these platinum complexes were analyzed by DFT calculations at the B3LYP level. The organoplatinum(II) complexes derived from the deformed scaffolds can serve as potent triplet sensitizers for singlet oxygen generation under aerobic conditions.
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- Authors: Pushpanandan, Poornenth , Maurya, Yogesh Kumar , Omagari, Toshihiro , Hirosawa, Ryuji , Ishida, Masatoshi , Mori, Shigeki , Yasutake, Yuhsuke , Fukatsu, Susumu , Mack, John , Nyokong, Tebello , Furuta, Hiroyuki
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233144 , vital:50061 , xlink:href="https://doi.org/10.1021/acs.inorgchem.7b02047"
- Description: Organoplatinum(II) complexes of calix[4]phyrin analogues, singly N-confused calix[4]phyrin (Pt-2), and doubly N-confused calix[4]phyrin (Pt-3), were synthesized and characterized. The explicit structures of these organoplatinum(II) complexes were elucidated by single-crystal X-ray diffraction and spectroscopic studies. The introduction of N-confused pyrrole rings to the parent calix[4]phyrin scaffold was found to have profound effects on the photophysical properties, such as the bathochromic shifts of both the absorption and phosphorescence maxima. The triplet excited state properties of these platinum complexes were analyzed by DFT calculations at the B3LYP level. The organoplatinum(II) complexes derived from the deformed scaffolds can serve as potent triplet sensitizers for singlet oxygen generation under aerobic conditions.
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Effects of charge on the photophysicochemical properties of zinc phthalocyanine derivatives doped onto silica nanoparticles
- Peteni, Siwaphiwe, Sekhosana, Kutloano E, Britton, Jonathan, Nyokong, Tebello
- Authors: Peteni, Siwaphiwe , Sekhosana, Kutloano E , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188159 , vital:44728 , xlink:href="https://doi.org/10.1016/j.poly.2017.09.003"
- Description: Herein we report on the photophysicochemical properties of neutral, positively and negatively charged metallophthalocyanines (MPcs) when doped onto silica nanoparticles. The MPcs are: unsubstituted ZnPc (complex 1, neutral), Zn tetraaminophenoxy phthalocyanine (ZnTAPhPc, complex 2, neutral), tetrakis[4-(iodo-N-methylpyridinium)thio] phthalocyanine (ZnTMPyPc, complex 3, cationic), and Zn tetra sulfophenoxy phthalocyanine (ZnTSPhPc, complex 4, anionic). Following doping onto SiNPs, the triplet quantum yields increased for neutral complex 1 and positively charged complex 3. However, singlet oxygen quantum yields increased for positively charged 3 (in 3-SiNPs) and the negatively charge 4 (in 4-SiNPs) and not for complex 1 (in 1-SiNPs), compared to Pcs alone, due to the screening effect.
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- Authors: Peteni, Siwaphiwe , Sekhosana, Kutloano E , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188159 , vital:44728 , xlink:href="https://doi.org/10.1016/j.poly.2017.09.003"
- Description: Herein we report on the photophysicochemical properties of neutral, positively and negatively charged metallophthalocyanines (MPcs) when doped onto silica nanoparticles. The MPcs are: unsubstituted ZnPc (complex 1, neutral), Zn tetraaminophenoxy phthalocyanine (ZnTAPhPc, complex 2, neutral), tetrakis[4-(iodo-N-methylpyridinium)thio] phthalocyanine (ZnTMPyPc, complex 3, cationic), and Zn tetra sulfophenoxy phthalocyanine (ZnTSPhPc, complex 4, anionic). Following doping onto SiNPs, the triplet quantum yields increased for neutral complex 1 and positively charged complex 3. However, singlet oxygen quantum yields increased for positively charged 3 (in 3-SiNPs) and the negatively charge 4 (in 4-SiNPs) and not for complex 1 (in 1-SiNPs), compared to Pcs alone, due to the screening effect.
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First example of nonlinear optical materials based on nanoconjugates of sandwich phthalocyanines with quantum dots
- Oluwole, David O, Yagodin, Alexey V, Mkhize, Nhlakanipho C, Sekhosana, Kutloana E, Martynov, Alexander G, Gorbunova, Yulia G, Tsivadze, Aslan Yu, Nyokong, Tebello
- Authors: Oluwole, David O , Yagodin, Alexey V , Mkhize, Nhlakanipho C , Sekhosana, Kutloana E , Martynov, Alexander G , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238014 , vital:50577 , xlink:href="https://doi.org/10.1002/chem.201604401"
- Description: We report original, selective, and efficient approaches to novel nonlinear optical (NLO) materials, namely homoleptic double- and triple-decker europium(III) complexes 2 and 3 with the A3B-type phthalocyanine ligand (2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-n-butoxyphthalocyanine 1) bearing two anchoring diethyleneglycol chains terminated with OH groups. Their covalently linked nanoconjugates with mercaptosuccinic acid-capped ternary CdSeTe/CdTeS/ZnSeS quantum dots are prepared in the presence of an ethyl(dimethylaminopropyl)carbodiimide activating agent. Optical limiting (OL) properties of the obtained low-symmetry complexes and their conjugates with quantum dots (QDs) are measured for the first time by the open-aperture Z-scan technique (532 nm laser and pulse rate of 10 ns). For comparison, symmetrical double- and triple-decker EuIII octa-n-butoxyphthalocyaninates 5 and 6 and their mixtures with trioctylphosphine oxide-capped QDs are also synthesized and studied. It is revealed that both lowering of molecular symmetry and expansion of the π-electron system upon moving from double- to triple-decker complexes significantly improves the OL characteristics, making the low-symmetry triple-decker complex 3 the most efficient optical limiter in the studied family of sandwich complexes, affording 50 % lowering of light transmittance below 0.5 J cm−2 input fluence. Conjugation (both covalent and noncovalent) with QDs affords further enhancement of the OL properties of both double- and triple-decker complexes. Altogether, the obtained results contribute to the development of novel nonlinear optical materials for future nanoelectronic and optical device applications.
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- Authors: Oluwole, David O , Yagodin, Alexey V , Mkhize, Nhlakanipho C , Sekhosana, Kutloana E , Martynov, Alexander G , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238014 , vital:50577 , xlink:href="https://doi.org/10.1002/chem.201604401"
- Description: We report original, selective, and efficient approaches to novel nonlinear optical (NLO) materials, namely homoleptic double- and triple-decker europium(III) complexes 2 and 3 with the A3B-type phthalocyanine ligand (2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-n-butoxyphthalocyanine 1) bearing two anchoring diethyleneglycol chains terminated with OH groups. Their covalently linked nanoconjugates with mercaptosuccinic acid-capped ternary CdSeTe/CdTeS/ZnSeS quantum dots are prepared in the presence of an ethyl(dimethylaminopropyl)carbodiimide activating agent. Optical limiting (OL) properties of the obtained low-symmetry complexes and their conjugates with quantum dots (QDs) are measured for the first time by the open-aperture Z-scan technique (532 nm laser and pulse rate of 10 ns). For comparison, symmetrical double- and triple-decker EuIII octa-n-butoxyphthalocyaninates 5 and 6 and their mixtures with trioctylphosphine oxide-capped QDs are also synthesized and studied. It is revealed that both lowering of molecular symmetry and expansion of the π-electron system upon moving from double- to triple-decker complexes significantly improves the OL characteristics, making the low-symmetry triple-decker complex 3 the most efficient optical limiter in the studied family of sandwich complexes, affording 50 % lowering of light transmittance below 0.5 J cm−2 input fluence. Conjugation (both covalent and noncovalent) with QDs affords further enhancement of the OL properties of both double- and triple-decker complexes. Altogether, the obtained results contribute to the development of novel nonlinear optical materials for future nanoelectronic and optical device applications.
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The effect of point of substitution and silver based nanoparticles on the photophysical and optical nonlinearity of indium carboxyphenoxy phthalocyanine
- Oluwole, David O, Ngxeke, Sixolisile M, Britton, Jonathan, Nyokong, Tebello
- Authors: Oluwole, David O , Ngxeke, Sixolisile M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188596 , vital:44768 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.07.032"
- Description: Indium(III) chloride 1,8(11),15(18),22(25)-tetra-(3-carboxyphenoxy) phthalocyanine (1) and indium(III) chloride 2,9(10),16(17),23(24)-tetra–(3-carboxyphenoxy) phthalocyanine (2) were covalently linked to glutathione capped silver nanoparticles (AgNPs–GSH) and silver selenide/zinc sulfide (Ag2Se/ZnS–GSH) quantum dots via amide bond formation. The photophysical and nonlinear optical behaviour of the metallophthalocyanines and their conjugates with nanoparticles were investigated using the open aperture Z–scan technique. Complex 2 showed enhanced photophysical properties compared to 1. The conjugates revealed improved triplet state quantum yields (except for 1-AgNPs-GSH which afforded lower triplet state quantum yields in comparison to 1) and nonlinear optical activities in comparison to the Pc complexes. The synthesized complexes, nanoparticles and their conjugates could be potential nonlinear optical materials due to their good nonlinear optical activities.
- Full Text:
- Authors: Oluwole, David O , Ngxeke, Sixolisile M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188596 , vital:44768 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.07.032"
- Description: Indium(III) chloride 1,8(11),15(18),22(25)-tetra-(3-carboxyphenoxy) phthalocyanine (1) and indium(III) chloride 2,9(10),16(17),23(24)-tetra–(3-carboxyphenoxy) phthalocyanine (2) were covalently linked to glutathione capped silver nanoparticles (AgNPs–GSH) and silver selenide/zinc sulfide (Ag2Se/ZnS–GSH) quantum dots via amide bond formation. The photophysical and nonlinear optical behaviour of the metallophthalocyanines and their conjugates with nanoparticles were investigated using the open aperture Z–scan technique. Complex 2 showed enhanced photophysical properties compared to 1. The conjugates revealed improved triplet state quantum yields (except for 1-AgNPs-GSH which afforded lower triplet state quantum yields in comparison to 1) and nonlinear optical activities in comparison to the Pc complexes. The synthesized complexes, nanoparticles and their conjugates could be potential nonlinear optical materials due to their good nonlinear optical activities.
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Optical limiters with improved performance based on nanoconjugates of thiol substituted phthalocyanine with CdSe quantum dots and Ag nanoparticles
- Oluwole, David O, Yagodin, Alexey V, Britton, Jonathan, Martynov, Alexander G, Gorbunova, Yulia G, Tsivadze, Aslan Yu, Nyokong, Tebello
- Authors: Oluwole, David O , Yagodin, Alexey V , Britton, Jonathan , Martynov, Alexander G , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238286 , vital:50605 , xlink:href="https://doi.org/10.1039/C7DT03867D"
- Description: Two alternative synthetic approaches affording a low-symmetry A3B-type phthalocyanine 1 bearing two [2′-(2′′-mercaptoethoxy)ethoxy] anchoring substituents were developed. Due to the presence of thiol groups, this phthalocyanine could be conjugated with TOPO-capped (TOPO - trioctylphosphine)-capped CdSe quantum dots (CdSe-QDs) or oleylamine capped silver nanoparticles (Ag-NPs). The nonlinear optical behaviour of starting phthalocyanine, quantum dots, nanoparticles and their conjugates was studied by using an open aperture Z-scan technique, revealing that the grafting of 1 onto the nanomaterials resulted in a significant enhancement of the optical limiting of 1-Ag and 1-CdSe in comparison with the individual components. The conjugate 1-CdSe, being the first example of Pc-based thiol conjugated with quantum dots, revealed superior limiting characteristics with a limiting threshold below 0.18 J cm−2.
- Full Text:
- Authors: Oluwole, David O , Yagodin, Alexey V , Britton, Jonathan , Martynov, Alexander G , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/238286 , vital:50605 , xlink:href="https://doi.org/10.1039/C7DT03867D"
- Description: Two alternative synthetic approaches affording a low-symmetry A3B-type phthalocyanine 1 bearing two [2′-(2′′-mercaptoethoxy)ethoxy] anchoring substituents were developed. Due to the presence of thiol groups, this phthalocyanine could be conjugated with TOPO-capped (TOPO - trioctylphosphine)-capped CdSe quantum dots (CdSe-QDs) or oleylamine capped silver nanoparticles (Ag-NPs). The nonlinear optical behaviour of starting phthalocyanine, quantum dots, nanoparticles and their conjugates was studied by using an open aperture Z-scan technique, revealing that the grafting of 1 onto the nanomaterials resulted in a significant enhancement of the optical limiting of 1-Ag and 1-CdSe in comparison with the individual components. The conjugate 1-CdSe, being the first example of Pc-based thiol conjugated with quantum dots, revealed superior limiting characteristics with a limiting threshold below 0.18 J cm−2.
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Photophysicochemical behaviour of metallophthalocyanines when doped onto silica nanoparticles
- Oluwole, David O, Nyokong, Tebello
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188518 , vital:44761 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.08.053"
- Description: Aluminum(III) chloride 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (1), zinc(II) 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (2), zinc(II) 1,8(11),15(18),22(25)–tetra–(4–tert–butylphenoxy) phthalocyanine (3) and zinc(II) 2,9(10),16(17),23(24)–tetra–(4–carboxylphenoxy) phthalocyanine (4) were doped onto silica nanoparticles (SiNPs). There were no significant changes in fluorescence quantum yields and lifetimes of the metallophthalocyanines ( MPcs) when doped onto SiNPs. The triplet quantum yields of the MPcs alone range from 0.22 to 0.85 and in the presence of SiNPs the values range from 0.17 to 0.89. We observed a general decrease of triplet quantum yields of phthalocyanines in the conjugates except for 2 where there was an increase. The values were highly affected by aggregation. Complexes 1 and 3 were highly aggregated when doped onto SiNPs, while 2 and 4 did not show much aggregation.
- Full Text:
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188518 , vital:44761 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.08.053"
- Description: Aluminum(III) chloride 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (1), zinc(II) 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (2), zinc(II) 1,8(11),15(18),22(25)–tetra–(4–tert–butylphenoxy) phthalocyanine (3) and zinc(II) 2,9(10),16(17),23(24)–tetra–(4–carboxylphenoxy) phthalocyanine (4) were doped onto silica nanoparticles (SiNPs). There were no significant changes in fluorescence quantum yields and lifetimes of the metallophthalocyanines ( MPcs) when doped onto SiNPs. The triplet quantum yields of the MPcs alone range from 0.22 to 0.85 and in the presence of SiNPs the values range from 0.17 to 0.89. We observed a general decrease of triplet quantum yields of phthalocyanines in the conjugates except for 2 where there was an increase. The values were highly affected by aggregation. Complexes 1 and 3 were highly aggregated when doped onto SiNPs, while 2 and 4 did not show much aggregation.
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Photophysical behavior and photodynamic therapy activity of conjugates of zinc monocarboxyphenoxy phthalocyanine with human serum albumin and chitosan
- Oluwole, David O, Prinsloo, Earl, Nyokong, Tebello
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188497 , vital:44759 , xlink:href="https://doi.org/10.1016/j.saa.2016.09.032"
- Description: Zincmonocarboxyphenoxy phthalocyanine (ZnMCPPc) was linked to human serum albumin (HSA) and chitosan via amide bond formation. The photophysical behavior and photodynamic therapy (PDT) activity (against human breast adenocarcinoma cell line (MCF-7 cells) of ZnMCPPc alone and its conjugates were investigated. The conjugates showed improved fluorescence, triplet and singlet oxygen quantum yields when compared to ZnMCPPc alone. The in vitro dark cytotoxicity and PDT studies were carried out at a dose of 3.6 μg/mL to 57.1 μg/mL. The in vitro dark cytotoxicity studies of ZnMCPPc showed cell viability more than 50% at 28.6 μg/mL and 57.1 μg/mL, while the conjugates showed > 50% in all their tested concentrations (3.6 to 57.1) μg/mL. Thus, conjugation of ZnMCPPc to HSA and chitosan improves its dark cytotoxicity, an important criteria for molecules meant for photodynamic therapy. Complex 1 showed the most efficacious PDT activity with cell viability more than 50% at concentration range of (14.3 to 57.1) μg/mL in comparison to the conjugates which only showed more than 50% cell viability at 28.6 μg/mL and 57.1 μg/mL for 1-HSA and 57.1 μg/mL for 1-Chitosan.
- Full Text:
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188497 , vital:44759 , xlink:href="https://doi.org/10.1016/j.saa.2016.09.032"
- Description: Zincmonocarboxyphenoxy phthalocyanine (ZnMCPPc) was linked to human serum albumin (HSA) and chitosan via amide bond formation. The photophysical behavior and photodynamic therapy (PDT) activity (against human breast adenocarcinoma cell line (MCF-7 cells) of ZnMCPPc alone and its conjugates were investigated. The conjugates showed improved fluorescence, triplet and singlet oxygen quantum yields when compared to ZnMCPPc alone. The in vitro dark cytotoxicity and PDT studies were carried out at a dose of 3.6 μg/mL to 57.1 μg/mL. The in vitro dark cytotoxicity studies of ZnMCPPc showed cell viability more than 50% at 28.6 μg/mL and 57.1 μg/mL, while the conjugates showed > 50% in all their tested concentrations (3.6 to 57.1) μg/mL. Thus, conjugation of ZnMCPPc to HSA and chitosan improves its dark cytotoxicity, an important criteria for molecules meant for photodynamic therapy. Complex 1 showed the most efficacious PDT activity with cell viability more than 50% at concentration range of (14.3 to 57.1) μg/mL in comparison to the conjugates which only showed more than 50% cell viability at 28.6 μg/mL and 57.1 μg/mL for 1-HSA and 57.1 μg/mL for 1-Chitosan.
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Electrode modification through click chemistry using Ni and Co alkyne phthalocyanines for electrocatalytic detection of hydrazine
- O'Donoghue, Charles S, Shumba, Munyaradzai, Nyokong, Tebello
- Authors: O'Donoghue, Charles S , Shumba, Munyaradzai , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233032 , vital:50049 , xlink:href="https://doi.org/10.1002/elan.201700084"
- Description: This work reports on the development of sensors for the detection of hydrazine using glassy carbon electrodes (GCE) modified with phthalocyanines through click chemistry. Tetrakis(5-hexyn-oxy) cobalt(II) phthalocyanine (complex 2) and tetrakis(5-hexyn-oxy) nickel(II) phthalocyanine (complex 3) were employed as electrode modifiers for hydrazine detection. The GCE was first grafted via the in situ diazotization of a diazonium salt, rendering the GCE surface layered with azide groups. From this point, the 1, 3-dipolar cycloaddition reaction, catalysed by a copper catalyst was utilised to “click” the phthalocyanines to the surface of the grafted GCE. The modified electrodes were characterized by scanning electrochemical microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry. The electrografted CoP2-clicked-GCE and NiP3-clicked-GCE exhibited electrocatalytic activity towards the detection of hydrazine. The limit of detection (LoD) for the CoPc-GCE was 6.09 μM, while the NiPc-GCE had a LoD of 8.69 μM. The sensitivity was 51.32 μA mM−1 for the CoPc-GCE and 111.2 μA mM−1 for the NiPc-GCE.
- Full Text:
- Authors: O'Donoghue, Charles S , Shumba, Munyaradzai , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233032 , vital:50049 , xlink:href="https://doi.org/10.1002/elan.201700084"
- Description: This work reports on the development of sensors for the detection of hydrazine using glassy carbon electrodes (GCE) modified with phthalocyanines through click chemistry. Tetrakis(5-hexyn-oxy) cobalt(II) phthalocyanine (complex 2) and tetrakis(5-hexyn-oxy) nickel(II) phthalocyanine (complex 3) were employed as electrode modifiers for hydrazine detection. The GCE was first grafted via the in situ diazotization of a diazonium salt, rendering the GCE surface layered with azide groups. From this point, the 1, 3-dipolar cycloaddition reaction, catalysed by a copper catalyst was utilised to “click” the phthalocyanines to the surface of the grafted GCE. The modified electrodes were characterized by scanning electrochemical microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry. The electrografted CoP2-clicked-GCE and NiP3-clicked-GCE exhibited electrocatalytic activity towards the detection of hydrazine. The limit of detection (LoD) for the CoPc-GCE was 6.09 μM, while the NiPc-GCE had a LoD of 8.69 μM. The sensitivity was 51.32 μA mM−1 for the CoPc-GCE and 111.2 μA mM−1 for the NiPc-GCE.
- Full Text:
Electrode modification through click chemistry using Ni and Co alkyne phthalocyanines for electrocatalytic detection of hydrazine
- O'Donoghue, Charles S, Shumba, Munyaradzai, Nyokong, Tebello
- Authors: O'Donoghue, Charles S , Shumba, Munyaradzai , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242763 , vital:51076 , xlink:href="https://doi.org/10.1002/elan.201700084"
- Description: This work reports on the development of sensors for the detection of hydrazine using glassy carbon electrodes (GCE) modified with phthalocyanines through click chemistry. Tetrakis(5-hexyn-oxy) cobalt(II) phthalocyanine (complex 2) and tetrakis(5-hexyn-oxy) nickel(II) phthalocyanine (complex 3) were employed as electrode modifiers for hydrazine detection. The GCE was first grafted via the in situ diazotization of a diazonium salt, rendering the GCE surface layered with azide groups. From this point, the 1, 3-dipolar cycloaddition reaction, catalysed by a copper catalyst was utilised to “click” the phthalocyanines to the surface of the grafted GCE. The modified electrodes were characterized by scanning electrochemical microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry. The electrografted CoP2-clicked-GCE and NiP3-clicked-GCE exhibited electrocatalytic activity towards the detection of hydrazine. The limit of detection (LoD) for the CoPc-GCE was 6.09 μM, while the NiPc-GCE had a LoD of 8.69 μM. The sensitivity was 51.32 μA mM−1 for the CoPc-GCE and 111.2 μA mM−1 for the NiPc-GCE.
- Full Text:
- Authors: O'Donoghue, Charles S , Shumba, Munyaradzai , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242763 , vital:51076 , xlink:href="https://doi.org/10.1002/elan.201700084"
- Description: This work reports on the development of sensors for the detection of hydrazine using glassy carbon electrodes (GCE) modified with phthalocyanines through click chemistry. Tetrakis(5-hexyn-oxy) cobalt(II) phthalocyanine (complex 2) and tetrakis(5-hexyn-oxy) nickel(II) phthalocyanine (complex 3) were employed as electrode modifiers for hydrazine detection. The GCE was first grafted via the in situ diazotization of a diazonium salt, rendering the GCE surface layered with azide groups. From this point, the 1, 3-dipolar cycloaddition reaction, catalysed by a copper catalyst was utilised to “click” the phthalocyanines to the surface of the grafted GCE. The modified electrodes were characterized by scanning electrochemical microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry. The electrografted CoP2-clicked-GCE and NiP3-clicked-GCE exhibited electrocatalytic activity towards the detection of hydrazine. The limit of detection (LoD) for the CoPc-GCE was 6.09 μM, while the NiPc-GCE had a LoD of 8.69 μM. The sensitivity was 51.32 μA mM−1 for the CoPc-GCE and 111.2 μA mM−1 for the NiPc-GCE.
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Improved nonlinear optical behaviour of ball type indium (III) phthalocyanine linked to glutathione capped nanoparticles
- Nwaji, Njemuwa, Oluwole, David O, Mack, John, Louzada, Marcel, Khene, Samson M, Britton, Jonathan, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Oluwole, David O , Mack, John , Louzada, Marcel , Khene, Samson M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239654 , vital:50752 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.01.066"
- Description: The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.
- Full Text:
- Authors: Nwaji, Njemuwa , Oluwole, David O , Mack, John , Louzada, Marcel , Khene, Samson M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239654 , vital:50752 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.01.066"
- Description: The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.
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Synthesis, photophysical and nonlinear optical properties of a series of ball-type phthalocyanines in solution and thin films
- Nwaji, Njemuwa, Mack, John, Britton, Jonathan, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Mack, John , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188976 , vital:44803 , xlink:href="https://doi.org/10.1039/C6NJ03662G"
- Description: In this study, we report on the enhanced nonlinear optical properties of novel tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato zinc(II)) (4), tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato gallium chloride) (5) and tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato indium chloride) (6) both in solution and when embedded in polymer thin films. Complexes 5 and 6 bearing heavy atoms showed enhanced triplet quantum yield and nonlinear optical response. The nonlinear third-order susceptibility and second-order hyperpolarizability values are also reported. Time dependent density functional theory (TD-DFT) calculations were performed in order to explain the origin of the observed UV-vis and magnetic circular dichroism (MCD) spectra of the complexes.
- Full Text:
- Authors: Nwaji, Njemuwa , Mack, John , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188976 , vital:44803 , xlink:href="https://doi.org/10.1039/C6NJ03662G"
- Description: In this study, we report on the enhanced nonlinear optical properties of novel tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato zinc(II)) (4), tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato gallium chloride) (5) and tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato indium chloride) (6) both in solution and when embedded in polymer thin films. Complexes 5 and 6 bearing heavy atoms showed enhanced triplet quantum yield and nonlinear optical response. The nonlinear third-order susceptibility and second-order hyperpolarizability values are also reported. Time dependent density functional theory (TD-DFT) calculations were performed in order to explain the origin of the observed UV-vis and magnetic circular dichroism (MCD) spectra of the complexes.
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Photophysical and nonlinear optical study of benzothiazole substituted phthalocyanines in solution and thin films
- Nwaji, Njemuwa, Bankole, Owolabi M, Britton, Jonathan, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Bankole, Owolabi M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233088 , vital:50055 , xlink:href="https://doi.org/10.1142/S1088424617500079"
- Description: In this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of zinc and gallium phthalocyanine complexes: tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato]zinc(II) (3), tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6), were investigated both in solution and when embedded in polystyrene thin films using 532 nm laser excitation at 10 ns pulses. It was also observed that complexes that have higher triplet state absorption also possessed enhanced nonlinear and optical limiting behavior. Superior optical performance was observed when the complexes were embedded in thin films compared to when they are in solution. Complex 6 in thin films gave the highest imaginary third-order susceptibility (Imm[X(3)(3)]) and hyperpolarizability (γ)γ) at 4.61 × 10-7-7 esu and 3.44 × 10-26-26 esu, respectively, with a low Ilimlim value of 0.06 J.cm-2.
- Full Text:
- Authors: Nwaji, Njemuwa , Bankole, Owolabi M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233088 , vital:50055 , xlink:href="https://doi.org/10.1142/S1088424617500079"
- Description: In this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of zinc and gallium phthalocyanine complexes: tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato]zinc(II) (3), tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6), were investigated both in solution and when embedded in polystyrene thin films using 532 nm laser excitation at 10 ns pulses. It was also observed that complexes that have higher triplet state absorption also possessed enhanced nonlinear and optical limiting behavior. Superior optical performance was observed when the complexes were embedded in thin films compared to when they are in solution. Complex 6 in thin films gave the highest imaginary third-order susceptibility (Imm[X(3)(3)]) and hyperpolarizability (γ)γ) at 4.61 × 10-7-7 esu and 3.44 × 10-26-26 esu, respectively, with a low Ilimlim value of 0.06 J.cm-2.
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Nanosecond optical nonlinearities in low symmetry phthalocyanine nanoconjugates studied using the Z-scan technique
- Nwaji, Njemuwa, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188172 , vital:44729 , xlink:href="https://doi.org/10.1016/j.jlumin.2017.08.053"
- Description: In this study, the photophysical, and nonlinear optical limiting properties of low symmetry tris[(4-benzo[d] thiazol-2-ylphenoxy)-2-phenoxyl acetic acid phthalocyaninato] zinc (II) (3) conjugated to metallic nanoparticles have been investigated using open aperture Z-scan techniques at 532 nm. The nonlinear optical response demonstrated that the studied complex and the nanoconjugates exhibits higher excited state absorption cross-section resulting from S1 and T1 compared to ground state absorption. Enhanced optical limiting performance was observed when the complex was conjugated to nanoparticles with 3SA-AuNPs showing the best optical limiting threshold of 0.39 J/cm2.
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- Authors: Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188172 , vital:44729 , xlink:href="https://doi.org/10.1016/j.jlumin.2017.08.053"
- Description: In this study, the photophysical, and nonlinear optical limiting properties of low symmetry tris[(4-benzo[d] thiazol-2-ylphenoxy)-2-phenoxyl acetic acid phthalocyaninato] zinc (II) (3) conjugated to metallic nanoparticles have been investigated using open aperture Z-scan techniques at 532 nm. The nonlinear optical response demonstrated that the studied complex and the nanoconjugates exhibits higher excited state absorption cross-section resulting from S1 and T1 compared to ground state absorption. Enhanced optical limiting performance was observed when the complex was conjugated to nanoparticles with 3SA-AuNPs showing the best optical limiting threshold of 0.39 J/cm2.
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